1. Field of the Invention
The present invention relates to display control apparatuses and methods for displaying an enlarged image.
2. Description of the Related Art
In current digital television broadcasting, standard definition (SD) content and high definition (HD) content are mixed. SD content is, for example, content having 720×480 pixels. HD content is, for example, content having 1280×720 or 1920 (1440)×1080 pixels. SD content and HD content are also mixed in storage media including digital versatile discs (DVDs), Internet broadcasting, video on demand (VOD), and the like.
A display capable of displaying SD content includes, for example, a display having 720×480 pixels. A display capable of displaying HD content includes, for example, a display having 1280×720 pixels or a display having 1920×1080 pixels. In recent years, an increasing number of HD-capable displays have been used.
Methods of displaying SD content on an HD-capable display can be roughly grouped into two types. The first type involves performing pixel conversion of SD content into the number of pixels of the HD-capable display and displaying an enlarged image of the SD content on the entire screen of the HD-capable display. The second type involves no pixel conversion of SD content and displays an image of the SD content on part of the screen of the HD-capable display.
Japanese Patent Laid-Open No. 11-4414 discloses a method of converting an SD image into an HD image. According to this method, an HD image corresponding to an original SD image is generated by performing a genetic operation. The HD image generated is converted into a second SD image which is then compared with the original SD image to evaluate the validity of the conversion result.
Research and development of content called “super hi-vision” having a higher resolution than HD and displays therefor have been conducted primarily by Nippon Hoso Kyokai (NHK) Science and Technical Research Laboratories. The image format of super high-vision content (hereinafter referred to as “SHV content”) is 7680×4320 (8 k×4 k) pixels. Digital cinemas having an image format of 4 k×2 k pixels have also been developed. An expected SHV-capable display includes, for example, a display having 7680×4320 (8 k×4 k) pixels and a display having 4096×2160 (4 k×2 k) pixels.
The number of pixels in HD content having 1920×1080 pixels is approximately six times greater than the number of pixels in SD content having 720×480 pixels. In contrast, the number of pixels in SHV content having 7680×4320 (8 k×4 k) is approximately 96 times greater than the number of pixels in SD content having 720×480 pixels. In the case where an enlarged image of SD content is displayed on the entire screen of the SHV-capable display having 8 k×4 k pixels, image quality is deteriorated when conventional pixel conversion is used. In contrast, in the case where an image of SD content is displayed without performing pixel conversion on the screen of the SHV-capable display having 8 k×4 k pixels, the image is displayed in only about one ninety-sixth of the area of the screen of the SHV-compliant display. Similarly, in the case where an image of SD content is displayed on a display having 4 k×2 k pixels, the image is displayed in only about one twenty-fourth of the area of the screen. In these cases, the displayed image likely will be unsatisfactory to a typical user.
In order to overcome these problems, it is desirable to display an image with the number of display pixels that is optimal for content (for example, the maximum number of display pixels with acceptable deterioration of image quality characteristics). In general, however, the number of pixels in the displayed images has conventionally either been implemented crudely or a user has been required to set the number of display pixels. No method of computing the number of display pixels that is optimal for content heretofore has been proposed.
Japanese Patent Laid-Open No. 11-4414 discloses a method of converting an SD image into an HD image. However, it does not describe the method of computing the number of display pixels that is optimal for content and then performing pixel conversion.